A variety of articles are formed from textiles. As examples, articles of apparel (e.g., shirts, pants, socks, footwear, jackets and other outerwear, briefs and other undergarments, hats and other headwear), containers (e.g., backpacks, bags), and upholstery for furniture (e.g., chairs, couches, car seats) are often at least partially formed from textiles. These textiles are often formed by weaving or interlooping (e.g., knitting) a yarn or a plurality of yarns, usually through a mechanical process involving looms or knitting machines. One particular object that may be formed from a textile is an upper for an article of footwear.
Knitting is an example of a process that may form a textile. Knitting may generally be classified as either weft knitting or warp knitting. In both weft knitting and warp knitting, one or more yarns are manipulated to form a plurality of intermeshed loops that define a variety of courses and wales. In weft knitting, which is more common, the courses and wales are perpendicular to each other and may be formed from a single yarn or many yarns. In warp knitting, the wales and courses run roughly parallel.
Although knitting may be performed by hand, the commercial manufacture of knitted components is generally performed by knitting machines. An example of a knitting machine for producing a weft knitted component is a V-bed flat knitting machine, which includes two needle beds that are angled with respect to each other. Rails extend above and parallel to the needle beds and provide attachment points for feeders, which move along the needle beds and supply yarns to needles within the needle beds. Standard feeders have the ability to supply a yarn that is utilized to knit, tuck, and float. In situations where an inlay yarn is incorporated into a knitted component, an inlay feeder is typically utilized.
One common problem with existing knitting machines is the inability to detect broken needles. When a needle breaks, it can interrupt the knit structure of a knitted component, which often requires the knitted component to be discarded as scrap. This problem may go undetected for extended periods of time, especially when the knitting machine is operating automatically without continuous human oversight.